maybe i should just get -- >> reporter: judge randy jackson explains why he thinks the heated exchanges between mariah carey and nikki minaj made news, and why it may continue. >> watch the tape back and you'll understand. >> really? is that what you do? is that what you do? >> you have to get to the point where you are always cool about disagreeing. i'm sure we'll have more of that. we're human. always take a minute, even with me, simon and paul. i was thinking back the other day, ryan, the first day of judging, with me, simon and paula, was insanity. >> you would have never thought we would have a second season. >> i think we had a five-hour break or something! >> reporter: next, it's off to hollywood, where the challenges will be both mental and physical, when the contestants compete with the best. >> you start warming up and you hear five, 10, 15, 30 other people that you think are better than you, and you go, wow! >> sharing rooms with people who snore, being frustrated, tired, being a little bit insecure that there are a lot of other people there, you know, with great voices and g